Which of the following is NOT a type of shipboard ventilation?

• A. Filtration
• B. Supply
• C. Exhaust
• D. Recirc

Answer: (A)

The main idea is telling apart how air is moved from how air is treated. In shipboard systems, ventilation types describe how air moves: supply brings fresh air in, exhaust pushes air out, and recirculation moves air within the spaces (often after mixing with some outdoor air). Filtration, while important for cleaning air, is a treatment step inside the system, not a method of moving air itself. It’s installed to remove particulates from the air that’s being moved, but it doesn’t define a ventilation mode. So filtration isn’t a type of shipboard ventilation, making it the correct choice.